Kallikrein and isorenin are enzymes which are frequently found in the same organs. They release potent vasoactive peptides (kinins and angiotensin) which could participate in the local regulation and distribution of blood flow. There is already evidence that intrarenal angiotensin could play a role in the regulation of renal blood flow. We plan to determine the possible participation of kallikrein and either renin or isorenin in the regulation of blood flow in the kidney, uterus and submaxillary glands of species that are known to have a high concentration of one or both of the enzymes in one of these organs. Total blood flow and its distribution will be measured by the microspheres technique during a control period, after angiotensin inhibition or kinin potentiation or inhibition. Blood pressure, GFR, water and electrolyte excretion, initiation of uterine contraction, and duration of labor and pregnancy will also be measured. These experiments could help to increase the knowledge of the factors that participate in the regulation of blood flow distribution. This is of importance since sodium and water excretion, edema formation, glandular secretion, and even the uterine contraction during initiation of labor could, at least in part, be regulated by changes in blood flow distribution.